Masters Theses

Date of Award

12-2022

Degree Type

Thesis

Degree Name

Master of Science

Major

Environmental Engineering

Major Professor

John S. Schwartz

Committee Members

John S. Schwartz, Jon M. Hathaway, Kelsey N. Ellis

Abstract

Probabilistic risk methods are becoming increasingly accepted as a means of carrying out risk-informed decision making regarding the design and operation of structures such as dams. Probabilistic risk calculations require the quantification of epistemic and aleatory uncertainties not investigated through deterministic methodologies. In this hydrological study, a stochastic sampling methodology is employed to investigate the joint failure probability of three dams in adjacent, similarly sized watersheds within the same Hydrologic Unit Code (HUC) 6 basin. A Probabilistic Flood Hazard Analysis (PFHA) framework is used to simulate the hydrologic loading of a wide range of extreme precipitation events across the combined watershed area of the three studied dams. Precipitation events are characterized by three distinct storm types influential in the Tennessee Valley region with implications for weather variability and climate change. The stochastic framework allows for the simulation of hundreds of thousands of spillway outflows which are used to produce empirical bivariate exceedance probabilities for spillway discharge pairs at selected dams. System response curves that indicate the probability of failure given spillway discharge are referenced for each dam and applied to generate empirical bivariate failure probability (joint failure probability) estimates. The stochastic simulation results indicate the range of spillway discharges for each pair of dams that pose the greatest risk of a joint failure. The estimate of joint failure considering the dependence of spillway discharges between dams is shown to be three to four orders of magnitude more likely than estimates that assume coincident failures are the result of independent hydrologic events.

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